DPM Error 33623 for Azure MABS

Question

DPM Error 33623 for Azure MABS

SOC 2 0

How to sort Data protection manager Error ID: 33623 for Azure MABS when doing backup of vmware esxi host

Suchitra Suregaunkar 11,805 Reputation points Microsoft External Staff Moderator

2026-03-09T16:34:22.55+00:00

Hello SOC 2

Thank You for posting your query on Microsoft Q&A platform.

We are looking into your issue and will keep you posted updates.

Thanks,

Suchitra.
Suchitra Suregaunkar 11,805 Reputation points Microsoft External Staff Moderator

2026-03-09T20:02:33.2533333+00:00
Hello SOC 2

When adding a VMware vCenter or ESXi host to Azure Backup Server (MABS), the operation fails with:

Error ID: 33623

Detailed error:

Unable to communicate with VMware Server

Internal error code: 0x80990EF2

This typically occurs during Add vCenter Server or Add Production Server steps.

The most common root cause is a TLS protocol mismatch:

Azure MABS / DPM uses older TLS defaults

ESXi 6.7 and later ONLY support TLS 1.2

If TLS 1.2 is not explicitly enabled on the MABS server, the SSL handshake fails, resulting in Error 33623

As a resolution please try below Workarounds.

1. Enable TLS 1.2 on the Azure MABS Server :

Set the following registry keys on the MABS server, then reboot.

Important: These settings are required even on Windows Server 2019 / 2022.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727] "SystemDefaultTlsVersions"=dword:00000001 "SchUseStrongCrypto"=dword:00000001 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319] "SystemDefaultTlsVersions"=dword:00000001 "SchUseStrongCrypto"=dword:00000001 [HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v2.0.50727] "SystemDefaultTlsVersions"=dword:00000001 "SchUseStrongCrypto"=dword:00000001 [HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319] "SystemDefaultTlsVersions"=dword:00000001 "SchUseStrongCrypto"=dword:00000001

This forces MABS to use TLS 1.2 for all .NET‑based communication, which ESXi accepts.

2. Restart the Azure MABS Server :

A reboot is mandatory for the TLS settings to take effect.

Re‑add the VMware Credentials in MABS:

After restart:

Open Azure Backup Server Console

Go to Management → Production Servers

Remove the existing VMware account (if added)

Add it again, using:

vCenter preferred (not individual ESXi)

A VMware role with required permissions

If the above shared resolution didn't work, I request you to please share me the below details for further investigation on this issue?

Which ESXi and vCenter versions are you backing up (for example, ESXi 6.7 / 7.0 / 8.0)?

Are you adding the VMware environment via vCenter or directly via standalone ESXi host?

Which Azure Backup Server (MABS) version and update level is installed?

What Windows Server version is MABS installed on (2019 / 2022)?

Have TLS 1.2 registry settings been explicitly enabled on the MABS server and was the server rebooted afterward?

Is the failure happening while adding the vCenter/ESXi host, or later during protection group creation?

Can the MABS server access https://<vcenter-or-esxi>:443 successfully from a browser?

Are you using self‑signed VMware certificates or CA‑signed certificates?

Did you import the VMware root certificate into the MABS server or disable certificate validation?

What account is used to add the VMware server (role, permissions, local/root vs domain account)?

Are there any proxy, firewall, or SSL inspection devices between MABS and vCenter/ESXi?

Does the DPMRACurr.errlog show TLS or authentication‑related errors (for example, ‘remote party closed the transport stream’)?

Thanks,

Suchitra.
Suchitra Suregaunkar 11,805 Reputation points Microsoft External Staff Moderator

2026-03-10T19:54:03.78+00:00

Hello @SOC 2@SOC 2 Could you please let us know if the solution shared in the comment addressed your query. If you have any other questions or need further support, please feel free to contact us.

Thanks,
Suchitra.
Naveena Patlolla 9,390 Reputation points Microsoft External Staff Moderator

2026-03-15T15:36:21.8266667+00:00

Hello SOC 2
We haven't heard back from you. If you have any questions or need further assistance, feel free to reply and we’ll be happy to continue the conversation.